Figure 1. Robo4 expression patterns in embryonic zebrafish vascular development. Panels A through D show robo4 in situ (blue) across 20 (A) and 22 (D) somites in embryos. Panels B and C are high-power images of the trunk region of (A) and (D), respectively. (E) Wild-type embryo and (F) morpholino-injected embryo. Panels E and F depict trunk regions of 22-somite embryos double stained for flk RNA (blue, endothelial marker) and antibody to acetylated tubulin (brown, neuronal marker). N, notochord; ISV, intersomitic vessels. Black asterisks depict the location of ISVs, and the white asterisk depicts angioblasts.